#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
using namespace std;
void mid_search(double n)
{
    int flag = 0;
    if (n < 0)n = -n, flag = 1;
    double l = 0.0, r = 100.0;
    while (r - l > 1e-8)
    {
        double mid = (l + r) / 2;
        if (mid * mid * mid <= n)
        {
            l = mid;
        }
        else
        {
            r = mid;
        }
    }
    if(!flag)
    printf("%.6lf\n", l);
    else
        printf("-%.6lf\n", l);
}
int main()
{
    double n = 0;
    scanf("%lf", &n);
    mid_search(n);

    return 0;
}